JPS6168450A - Homogeneous gas phase nitration - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present process is a method for producing nitroparaffins by gas phase nitration of a hydrocarbon feed stock containing small amounts of carboxylic acids, either alone or in admixture with certain other oxygenated hydrocarbon compounds. Regarding. The process produces high yields of nitroparaffins and high percentages of nitroparaffins in the form of nitromethane.

Processes for producing nitroparaffins by gas phase nitration are known. U.S. Patent Nos. 3780115 and 386925
No. 3 teaches that nitration of saturated hydrocarbons higher than methane can be accomplished by contacting the hydrocarbon feed with nitrogen dioxide in the presence of oxygen, such as in air.

The reactant gas is preheated and then introduced into the reaction zone where the gas phase nitration is carried out at elevated pressure and temperature. The gas phase effluent exiting the nitration reaction zone is quenched. This quenched mixture then enters a separator where gaseous substances are removed for subsequent purification and circulation. The remaining organic and aqueous phase liquid materials are separated by decanting and the nitroparaffins are recovered by distillation. This nitration process gives a product mixture containing predominantly nitropropane.

French Patent Publication No. 78/32118 discloses that a product mixture of nitroparaffins is produced with ethane as the hydrocarbon feed;
It is disclosed that the most commercially desirable product, nitromethane, can be produced in increased yield by use in homogeneous gas phase nitration. This nitration process can be further enhanced by recycling some of the nitropropane product into the hydrocarbon feed and/or by carrying out the nitration in the presence of an inert gas such as nitrogen, hydrogen or argon. I can do it.

Similar to the French painting reference mentioned above, U.S. Patent No. 42608
No. 38 is based on U.S. Patent Nos. 3,780,115 and 3,869.
No. 253 teaches that the gas phase nitration process can be improved by varying the feedstock to obtain appropriate proportions of different nitroparaffins to suit market demands. This patent indicates that the feedstock is made from propane, preferably a mixture containing recycled nitroparaffins and possibly inert gases and/or other alkanes. The nitrating agent may be nitrogen peroxide or nitric acid.

Each of the conventional methods, such as those described in the referenced patents mentioned above, produce a mixture of nitroparaffinic products in low yields and/or the most commercially desired compound, nitromethane, in low yields.

A method has now been discovered for producing nitromethane in improved yields and with increased distribution by nitrating a hydrocarbon feed at elevated temperatures and pressures suitable for nitration in the homogeneous gas phase. . The feedstock for this process comprises saturated hydrocarbons higher than methane, nitrogen dioxide, element II and small amounts of at least one carboxylic acid or a mixture of said carboxylic acid and an oxygenated hydrocarbon.

The method is described in U.S. Pat. No. 378, cited by reference.
No. 0115, No. 3869253 and No. 4260838
This is an improvement on the known homogeneous gas phase nitration process carried out at elevated temperature and pressure, as disclosed in No. We now demonstrate that the presence of a small amount of at least one carboxylic acid in the nitration reaction zone, either as a mixture with at least one carboxylic acid or an oxygenated hydrocarbon such as It has been unexpectedly discovered that the distribution of nitromethane, the most commercially desirable compound of the nitroparaffins, increases.

"Carboxylic acid" as used in this disclosure and claims
refers to one or a mixture of monodicarboxylic acids < Ca to Cw (preferably C1 to Cs) as described in more detail below. As used in this disclosure and the claims, an "oxygenated hydrocarbon" refers to (a) a carbon atom which may be bonded by a single or double bond to a lower alkyl group, preferably a methyl or ethyl group; (b) 2 to 1 carbon atoms with at least one oxygen atom attached
O. Preferably it relates to organic compound(s) having from 2 to 5 and (C) from the group of compounds of alcohols, aldehydes, ketones and ethers. The most preferred oxygenated hydrocarbon compounds include at least one covalent bond (single bond or double bond) to an oxygen atom in the compound.
Compounds with a structure in which one carbon atom is also bonded to a methyl group, such as acetaldehyde, acetone, methyl ethyl ketone, ethanol, impropatol, 2
-7tanol, diethyl ether, methyl ethyl ether, etc.

The term "mixed oxygenate" in this disclosure and in the claims refers to a mixture of at least one carboxylic acid, as further described below, with at least one oxygenated hydrocarbon, as described below.

More particularly, the carboxylic acid or mixture thereof is a C2-CI monocarboxylic acid such as acetic acid, propionic acid, butyric acid, valeric acid,
It can be selected from caproic acid, caprylic acid, etc. Carboxylic acids are at least one type of C! -C5 monocarboxylic acids are preferred. The most preferred acid is acetic acid. Such carboxylic acids may be the only type of chargeable non-paraffinic material introduced into the reaction zone, or they may be introduced together with other oxygenated hydrocarbons as described below.

Oxygenated hydrocarbons useful in forming mixed oxides with at least one carboxylic acid include alcohols, preferably C
! ~C5 alcohols, such as ethanol, 1-propatool, 2-propatool, isopropatool, 2-butanol, tert-butanol, etc.: aldehydes, preferably C and ~Cs aldehydes, such as acetaldehyde, propionaldehyde, etc.; ketones, preferably C3 ~C
, ketones such as acetone, methyl ethyl ketone, diethyl ketone, etc.; and ethers, preferably C3-Cs ethers such as dimethyl ether, methyl ethyl ether, diethyl ether, methyl butyl ether, etc.

When using a mixed oxygenate feed, it is lower or C2
~Cs monocarboxylic acid compounds and C2-C5 oxygenated compounds and preferably C2 compounds such as acetaldehyde,
Preferably it consists of acetone, ethanol, acetic acid or diethyl ether or mixtures thereof. The proportions of the mixed oxygenate components will be determined primarily by economics and availability, provided that the carboxylic acid is present in the predominant amount and any other single component forms the mixed oxygenate feed.

The mixed oxygenate compound may be supplied from a by-product of the process, as described below, or it may be supplied from an external source, or it may be supplied only from an external source.

The carboxylic acids and oxygenated hydrocarbon compounds preferably do not contain non-hydrocarbon groups other than oxygen, as described above. However, the compound may contain non-hydrocarbon groups that do not interfere with the method.
For example, it may contain nitrile, halide, etc. The carboxylic acid and any oxygenated hydrocarbon feed used in accordance with the present invention may contain small amounts of lower or higher congeners of the above-mentioned compounds, provided they do not interfere with the unexpected results achieved herein. You can leave it there.

The carboxylic acid can be obtained by recycling at least a portion of the aqueous bottoms waste stream from the azeotropic distillation column of a conventional system. This stream mainly contains water and lower carboxylic acids.

The oxygenated hydrocarbons used to produce the mixed oxygenates are obtained by using at least a portion of the oxygenated hydrocarbon waste stream obtained as an overhead product from an oxygenate removal column in a conventional system. be able to. The overhead stream of the oxygenate removal column generally comprises a mixture of acetaldehyde and acetone in a ratio of about 1.5:1 to about 3:1 (about 4
0-80% by weight), and the remainder of the stream contains methanol, ethanol, formaldehyde and other substances in varying amounts.

Alternatively, the carboxylic acid and, if used, the oxygenated hydrocarbon feed may be supplied at least in part or in whole from external sources such as those available commercially.

Known processes, such as those disclosed in U.S. Pat. Do the following. The preheating conditions are preferably at substantially the same temperature and pressure as the reaction conditions.

The reactants are saturated hydrocarbon compounds or mixtures of such compounds. Hydrocarbons are C! or higher hydrocarbons, preferably 02 to C5 hydrocarbons, with ethane or propane or mixtures thereof being most preferred. A portion of the hydrocarbon feed may be recycled unreacted hydrocarbons that have been separated, purified and recondensed from the reaction products in a conventional manner.

Oxygen, usually in the form of air, and nitrogen peroxide (as used in this disclosure and in the claims, "nitrogen peroxide" and "nitrogen dioxide" respectively refer to the compound NO!
) or its precursors, such as N2O4, can be preheated separately or preferably mixed together and then preheated. Like the hydrocarbon feed, the nitrogen peroxide/oxygen feed feed can be obtained at least in part from unreacted recycle material separated and purified from the reaction products by conventional methods.

The feed may further contain inert gases such as nitrogen, carbon oxide, hydrogen, carbon dioxide, argon or mixtures thereof. Additionally, the feed may contain 1 nitrogen peroxide in the feed.
It may contain up to about 15 mole percent per mole of less desirable nitroparaffin compounds, such as 2-nitropropane.

The carboxylic feed, alone or as a mixture with oxygenated hydrocarbons, can be preheated to substantially the same temperature and pressure conditions as described above for each of the other feed streams, or otherwise preheated. May be combined with hydrocarbon feed.

The conditions and range of reaction factors for homogeneous gas phase nitration of hydrocarbons are as follows. The feedstock is a saturated hydrocarbon feed such as ethane or propane or mixtures thereof, such that the molar ratio of carbon atoms to nitrogen peroxide contained is about 8 to 12. 0. The molar ratio of and N O2 is approximately o.

It is 5 to 0.3. The reaction takes place when the fluid in the reactor is about 280 ~
A temperature of 520°C and about 5 to 30 bar, preferably 8 to 30 bar
It is carried out at elevated temperature, such as under an elevated pressure of 14 bar.

Inert gases in the feed (e.g. Ht, A, Go, G
o! ,N! > may be about o to 30% by volume.

The reaction contact time of the reaction gas in the reaction zone may be about 1 to 20 seconds, preferably about 4 to 12 seconds.

Referring to the drawings to illustrate the method, a hydrocarbon feed such as ethane, propane or mixtures thereof,
A conduit 1 leads to a preheater 2 from a receiver (not shown). Preheater 2 preheats the carboxylic acid alone or as a mixture with oxygenated hydrocarbons recycled through conduit 3 and/or from an external source through conduit 31, as will be described in more detail below. Also used for

The preheater essentially maintains a reaction zone inlet temperature of 330°C and a pressure of about 1
maintained at 0 bar. Preheated hydrocarbon/carvone!
! ! The (or mixed oxygenate) mixture is subsequently fed from conduit 4 to reactor inlet conduit 5. Nitrogen peroxide and oxygen (as air) are introduced into preheater 8 through conduits 6 and 7, respectively. This preheater 8 is maintained at substantially the same humidity and pressure conditions as the preheater 2. Mixed preheated N Ot/O
The gas enters the reactor inlet conduit 5 through conduit 9 by using a gas-gas mixing device such as a sparger, venturi, or the like. The preheated gas is approximately 330℃
Reaction 17A maintains a temperature of t8 and a pressure of about 10 bar.
Reactor 10, which may be in the form of a tubular reactor with
pass through. hot spots in the reactor
5pot) may be 420-520°C. Conduit 11
The reactor effluent removed from the reactor is cooled to room temperature in a cooler 12 that rapidly cools the gas using supercooled water.

The cooled reactor effluent is separated in separator 13. The liquid effluent separates into an organic liquid phase 14 and an aqueous liquid phase 15.

The uncondensed gaseous reaction effluent is passed through conduit 16 to separator 1
Remove from 3. The uncondensed gaseous reaction effluent is a mixture of components consisting primarily of unreacted hydrocarbon feed (eg, ethane, propane), nitrogen oxides, and inert gases. The gaseous reaction effluent is then treated in station 17 according to one of the conventional methods and then returned via reactor inlet 5 as part of the feed to reactor 10. This particular treatment mode chosen does not affect the invention. For illustrative purposes,
The gaseous effluent is prepared by <a) direct injection of M atoms into the gaseous effluent to reoxidize the nitrogen oxides to nitrogen peroxide;
)jl! or (C) removing the nitrogen oxides from the gaseous effluent by absorption into a ferrous sulfate solution. , which can then be treated by reoxidizing the nitrogen oxide to peroxide. The discharge stream 18 is maintained to prevent inert gas build-up due to gaseous effluent recirculation.

14 and 15 of the condensed organic and aqueous liquid phases, respectively;
It is removed from separator 13 and introduced into azeotropic distillation column 19 via conduits 14' and 15'.

This distillation column has a pressure of 1.25 bar or less and a
Operates at temperatures between 0 and 105°C. The mixture of nitroparaffins, as well as other compounds with lower boiling points than the nitroparaffins, including reaction zone by-product oxygenated hydrocarbons, are azeotropically distilled overhead with accompanying water, conduit 20, condenser 21
and enters oxygenate removal column 25 through conduit 22 . Some of the distillate can be recycled to the azeotrope 19 via conduit 23. . Most of the water and overprint products such as carboxylic acids (primarily acetic acid) are easily removed from conduit 24 as bottom product. This bottoms stream (previously considered a waste product and discarded) can be used as a source of carboxylic acid feed and can be recycled through conduit 30 to inlet 3 of heater 2.

Oxygenate removal column 25 operates at a pressure of 1.25 bar or less and a temperature range of 30-95°C. The bottom product of column 25 is removed in conduit 26 and consists of a large amount of nitroparaffin product, a small amount of water (from the previous azeotropic distillation),
May contain trace amounts of oxygenated hydrocarbon by-products. The material removed by conduit 26 is chemically treated (not shown) to remove trace oxygenated contaminants, then fed to a dehydration tower (not shown) and finally to a rectification tower. (
(not shown) to recover the pure nitroparaffin product.

The overhead effluent of column 25 passes through condenser 28 and is removed by conduit 27. The overhead effluent is usually very small compared to the bottom product and consists of a mixture of light oxygenated hydrocarbon compounds of lower alcohols, aldehydes, ketones and ethers. Generally, the majority of the overhead effluent is approximately 1.5:1 by weight.
It consists of a mixture of about 40-80% acetaldehyde and acetone in a ratio of ~3:1. Due to the small volume of this effluent, its mixed composition and the difficulty of purification into individual components, the column 25
In the past, spills were considered to be of little value and were usually incinerated. According to one embodiment of the invention, this overhead effluent can be used as a source of oxygenated hydrocarbons to produce a mixed oxygenate feed.

The carboxylic acid-containing bottoms stream of column 19 is combined with oxygen in column 25 to provide at least one carboxylic acid or a mixed oxygenate enriched in carboxylic acids, either alone or as part of the feed to nitration reactor 10. The utilization of carbonized hydrocarbon overhead products and/or materials from external sources provides high yields of 21-lobarafin product and nitroparaffin product in the form of the most desirable compound, nitromethane. It has been unexpectedly discovered that it can be manufactured in a fraction of the time. The amount of carboxylic acid or mixed oxygenate feed that may be present in reactor 10 is up to about 20% (about 0.1-20%) by weight of the hydrocarbon feed (fresh feed recycle), preferably It is 1 to 5% by weight.

The carboxylic acid from column 19 and the oxygenated hydrocarbon from column 25 each typically represent about 4-20% by weight of the fresh hydrocarbon feed entering t1. Separately or as part of the starting process, the above-mentioned substances, alone or as a mixture, for example acetaldehyde/acetic acid of about 1:1 to 1:3, in the above-mentioned amounts relative to the recycled materials, are introduced into the feed through conduit 31. May be introduced.

In any case, the presence of small amounts of at least one carboxylic acid in the total feed significantly shifts the distribution of the nitrobara-tween compounds, generally increasing the nitromethane concentration by 10 to 25
% higher yields.

The following examples are presented for illustrative purposes only and are not meant to limit the invention except as defined in the claims. All parts and percentages are by weight unless otherwise noted.

A homogeneous gas phase nitration reaction was compared using a control experiment in which the hydrocarbons (ethane/propane) alone were used and a small amount of acetic acid was introduced into the reaction zone along with the hydrocarbon feed according to conventional methods. In the first case the feed is ethane 38
25 (34%), propane 2928 (26%), nitrogen peroxide 1372 (12,3%), oxygen 462 (4%)
and nitrogen 2626 (23.4%) (all figures are in mmol/hour). 3 tubular reactors
It was carried out under isothermal conditions of 00° C. and 10 bar absolute pressure. The residence time was 6.8 seconds. The material was cooled, separated and azeotropically distilled to separate it from oxygenates. The recovered products were 5.8% nitromethane, 7.7% nitroethane,
1-nitropropane 5.4% and 2-nitropropane 2
It was 9%.

Co and COt totaled 16.4% and oxygenates about 28%.

Feed is ethane 3825 (33%), propane 277
4 (24%), acetic acid 281 (2%), nitrogen dioxide 1
528 (13%), oxygen 462 (4%) and nitrogen 262
6 (25%).

The products obtained were 8.4% nitromethane, 7.7% nitroethane, 6.2% 1-nitropropane and 28% 2-nitropropane. The total of CO and CO2 is 27
．． 5% and mixed oxygenate was 21.6%.

Feed is ethane 3825 (30%), propane 276
8 (22%), vinegar 111520 (12%), nitrogen dioxide 1434 (11%), oxygen 462 (3°7%) and nitrogen 2626 (21%). The product is 13.3% nitromethane,
Nitroethane was 4.8%, 1-nitropropane was 4.1% and 2-nitropropane was 17.5%. CO and C
O! total is 43.3% and mixed oxygenate is 5.4%.
It was only %.

It is clear that the presence of small amounts of oxygenated compounds in the reaction zone increases the yield of nitroparaffins and their distribution into nitromethane.

Although the invention has been described in connection with certain preferred embodiments, it is not intended to limit the invention to the particular forms described above. On the contrary, however, the invention is intended to cover alternatives, modifications, and equivalent embodiments as defined in the claims.

[Brief explanation of the drawing]

The drawing shows a flow sheet for carrying out the method of the invention. Patent applicant: W. R. Brace, Purification of Drawings] (No change in content, Procedural amendment statement) Dec. 7, 1980 Manabu Shiga, Commissioner of the Patent Office, 1, Patent Application No. 188264 (1982) No. 2, Name of the invention: Homogeneous vapor phase nitration method Company 4, Agent: 107 5, Date of amendment order: spontaneous) 6, Amended N-elephant drawing

Claims (1)

[Claims] 1. Contacting a hydrocarbon higher than methane or a mixture of hydrocarbons, nitrogen peroxide, and oxygen under elevated temperature and pressure in a reaction zone; cooling the reaction zone effluent; and the resulting liquid; In a homogeneous gas phase nitration process for producing nitroparaffins by separating the phase effluent from the noncondensable gaseous effluent; separating the organic nitroparaffin-containing phase from the liquid phase effluent; and recovering the nitroparaffins, the hydrocarbon, nitrogen peroxide and oxygen reactants within the reaction zone;
A small amount, up to about 20% by weight of the hydrocarbons present in the reaction zone, of (a) at least one C_2-C_1_0 carboxylic acid, or (b) at least one C_2-C_1_0 carboxylic acid and at least one a mixture of oxygenated hydrocarbons. 2. At least a portion of the reaction zone components selected from carboxylic acids, oxygenated hydrocarbons, or both present in the reaction zone during the separation and recovery of organic nitroparaffins contained in the liquid phase reaction zone effluent. A method according to claim 1 for obtaining. 3. The process of claim 1, wherein the reaction zone components selected from carboxylic acids and oxygenated hydrocarbons present in the reaction zone are obtained from sources other than the process. 4. The method according to claim 2, wherein the hydrocarbon is selected from ethane, propane or a mixture thereof. 5. The method according to claim 3, wherein the hydrocarbon is selected from ethane, propane or a mixture thereof. 6. The method according to claim 2, wherein the at least one carboxylic acid is selected from C_2 to C_5 monocarboxylic acids. 7. The method according to claim 3, wherein the at least one carboxylic acid is selected from C_2 to C_5 monocarboxylic acids. 8. At least one oxygenated hydrocarbon compound is selected from C_2 to C_5 organic compounds having at least one oxygen atom and at least one methyl group bonded to a common carbon atom. Method described. 9. At least one oxygenated hydrocarbon compound is selected from C_2 to C_5 organic compounds having at least one oxygen atom and at least one methyl group bonded to a common carbon atom.Claim 7 Method described. 10, the reaction zone is (a) at least one type of C_2 to C_1_
4. The method according to claim 3, which contains zero carboxylic acids. 11. The reaction zone is (a) at least one type of C_2 to C_1_
6. The method according to claim 5, containing 0 carboxylic acids. 12. The method according to claim 7, wherein the acid is acetic acid. 13. The method according to claim 10, wherein the acid is acetic acid. 14. The method according to claim 11, wherein the acid is acetic acid. 15. The method of claim 4, wherein mixture (b) is a mixture of acetaldehyde/acetic acid in a weight ratio of substantially from about 1:1 to 1:3. 16. The method of claim 5, wherein mixture (b) is a mixture of acetaldehyde/acetic acid in a weight ratio of substantially from about 1:1 to 1:3. 17. The process of claim 2, wherein the reaction zone feed mixture further contains up to 15 mole percent of at least one nitroparaffinic compound per 100 moles of nitrogen dioxide. 18. The process of claim 3, wherein the reaction zone feed mixture further contains up to 15 mole percent of at least one nitroparaffinic compound per 100 moles of nitrogen dioxide. 19. The process of claim 6, wherein the reaction zone feed mixture further contains up to 15 mole percent of at least one nitroparaffinic compound per 100 moles of nitrogen dioxide. 20. The process of claim 7, wherein the reaction zone feed mixture further contains up to 15 mole percent of at least one nitroparaffinic compound per 100 moles of nitrogen dioxide. 21. The reaction zone is subjected to a reaction pressure of 7 to 30 bar; 280 to 5
Reactant fluid temperature of 20°C; ratio of about 8 to 12 hydrocarbon carbon atoms to moles of nitrogen peroxide: about O. 05-0.3 O
11. The method of claim 10, wherein the molar ratio of NO_2 to NO_2 is maintained at a molar ratio of NO_2 to NO_2. 22. The reaction zone is subjected to a reaction pressure of 7 to 30 bar; 280 to 5
Reactant fluid temperature of 20°C; ratio of hydrocarbon carbon atoms to moles of nitrogen peroxide of about 8 to 12; O of about 0.05 to 0.3;
12. The method of claim 11, wherein the molar ratio of NO_2 to NO_2 is maintained at a molar ratio of NO_2 to NO_2.